There was a great blog posted by the marketeer Seth Godin. If he gets it, then everyone involved in project management should also. Here's what he wrote:

Why do ambitious projects often fail to meet our expectations? (Unambitious projects fail because they have low expectations). Why do software and other project teams so often get frustrated and stuck?

OVERPROMISING: During the magical early stages of the project, we envision not just perfect execution, but limitless features. At this stage, every project needs a truth teller (not a no-sayer, because they are easy to find and worthless, but a truth teller, someone who has been through it before and knows the difficulties that lie ahead).

"Everything takes more time than you thought, everything costs more money than you thought, and almost everything turns out not quite as cool as you expected." Merlin Mann

UNDERSHARING: As the project gets built, our instinct is to hide. Hide our roadblocks, our mistakes, our worries. As we hide, we keep the rest of the team in the dark. As the darkness settles in, it's easier than ever to keep hiding, because to unhide now is double the trouble.

LACK OF POLISH: The charette-driven, when's-the-deadline mindset might be a good way to force yourself through the resistance, but it has a huge cost--you will be judged. The market will not judge you by how much work you did, we will judge you by how it works and looks and feels. And that comes from polish, and polish cannot be rushed.

Two other thoughts on this:

1. Sometimes, all three of these stooges contribute to a piece of art. Sometimes, the audacity of being underinformed, combined with the ego strength of the final push over a deadline causes a magical thing to arrive. Bravo! But it's not dependable. If this is what you need to make art, then by all means, go for it. But be clear to each other about what's on the table.

2. The internet has made it possible to launch sloppy and polish in public. This is a form of oversharing, right? With thousands of people seeing each iteration, you can't hide what it looks like and you can't hide from the feedback. Here's what you need to understand about this: the launch isn't the end, it's the beginning. Back when I made books and software on floppies, you could say, "it's done." If you polish in public, that's never your option. It's not done. Have you planned for that?